By Chuck Hawks
Since the advent of smokeless powder, medium bore (.33-.39) calibers have not been very popular with North American hunters. We seem to prefer flatter shooting calibers that kick less, which actually makes a lot of sense for most North American hunting.
On the other hand, there are legitimate applications for medium bore hunting cartridges when hunting the largest or dangerous North American game, including moose, musk ox, the great bears, bison, and possibly Roosevelt elk. (Although so many Roosevelt elk have been cleanly harvested with small bore calibers such as the .270 Win, .30-30, .308 Win, and .30-06 that it would be absurd to claim that they are not adequate.) A medium bore bullet at moderate velocity also seems to be a little better than most small bore, high velocity projectiles at "brush bucking," although I never advise intentionally trying to drive a bullet through intervening foliage.
One thing is for certain, the medium bore calibers have gotten far more ink in the sporting press than their sales would seem to warrant. The result has been to keep interest in the medium bores bubbling. Hence this article comparing the standard North American medium bore cartridges.
(I know, the .350 Remington Magnum is a magnum cartridge both in name and in fact because it is based on a belted magnum case. But it is a shortened magnum case with actual powder capacity similar to that of the standard length .338-06 and .35 Whelen cartridges, which is why it is included here.)
Factory loads are not thick on the ground for any of these calibers. Most are offered by only one or two manufacturers and not widely distributed. The same can be said for factory built rifles in these calibers.
Two of these cartridges use .338" diameter bullets and the other three use .358" bullets. Both bullet diameters are available in a variety of styles and weights to reloaders. The most common .338" bullets weigh 180-185, 200-210, 225, and 250 grains. The most common .358" bullets weigh 150, 180, 200, 220-225, and 250 grains. Probably the most common bullet weights in both .338 and .358 are 200-210 grains, and these are the bullet weights most often encountered in factory loads.
All of these cartridges have moderate size cases and the sterling asset (for the reloader) of easily being reduced in velocity/power/recoil to deliver a 200 grain bullet at a MV of approximately 2400 fps. This type of medium velocity load does not require a special powder and makes these cartridges ideal for woods and brush country deer hunting as well as the pursuit of larger game. It is this versatility that is the greatest virtue of these cartridges, and what sets them apart from the more powerful medium bore magnums (.338 Win. Mag, .375 H&H, etc.).
This is the newest of the North American medium bore cartridges, and the rising star in the medium bore firmament. It was introduced in 2006 by Federal (ammunition) and Sako (rifles). It is based on the .308 Winchester necked-up to accept .338" diameter bullets, which makes it a true short action cartridge. Short action rifles are popular and numerous, and a year after its introduction the cartridge was also being offered by Ruger, Kimber, Tikka, Steyr/Mannlicher, and T/C.
The .338 Federal is loaded to rather higher pressure than the older .358 Winchester, which gives it a certain ballistic advantage. Otherwise, it is much like the .358 with the advantage of more shoulder on which to headspace and greater sectional density (SD) with bullets of the same weight.
Wildcatters have been necking-up .30-06 cases to accept .33 caliber bullets since at least the 1940's. But it was the introduction of a wide range of .338" bullets for reloading the .338 Win. Mag. in the late 1950's and early 1960's that breathed new life into the .338-06 cartridge. A-Square finally legitimized the .338-06 by standardizing it as a SAAMI cartridge and Weatherby and A-Square supply rifles and factory loaded ammunition in the caliber. Stars and Stripes is another source of .338-06 factory loads.
The .338-06 is naturally compared to the .35 Whelen, since both are based on necked-up .30-06 brass. As with the .338 Federal / .358 Winchester comparison, the .338-06 has the advantage of a larger shoulder and bullets of greater sectional density for a given weight.
The .358 Winchester was introduced back in 1955. It is based on a necked-up .308 case and over the years it has been offered in a variety of bolt and lever action rifles without ever really catching on. On the other hand, the .358 has held on due to a small but avid group of fanciers.
It is currently offered in the lever action Browning BLR and the bolt action Ruger M77, but since it is a short action caliber there are many rifles in which it could be chambered. Winchester and Stars and Stripes offer factory loaded ammunition.
Compared to the newer .338 Federal, the .358 offers greater frontal area with bullets of the same weight. I can testify that its .35 caliber bullet puts down animals with authority.
This old wildcat dates back to the early 1920's and is based on a .30-06 case necked-up to accept .358" bullets (.35-06). The .35 Whelen was finally standardized in 1987 by Remington after the stir caused by their introduction of their .350 Magnum renewed interest in this old wildcat of essentially equal performance. Federal, Remington, and Stars and Stripes offer factory loaded ammunition, and Remington offers rifles. Compared to the .338-06, the .35 Whelen punches a larger diameter hole with a bullet of the same weight.
.350 Remington Magnum
This is the only "magnum" cartridge in this comparison. The .350 Remington Magnum was introduced in the middle 1960's and is based on a shortened and necked-up .338 Winchester Magnum belted case. The belt and the fatter case mean that the relatively small shoulder does not create a headspace problem, as sometimes happens with the .358 Win. and .35 Whelen.
Since the .350 has about the same case capacity as the .35 Whelen and is loaded to slightly higher pressure, it offers a modest performance increase compared to the older cartridge, at least with factory loaded ammunition. And it does so in a cartridge overall length that allows it to work through today's popular short action rifles. At the present time Remington and Stars and Stripes offer factory loaded ammunition, while Remington and Ruger offer .350 rifles.
We will compare the velocity, energy, trajectory, sectional density, bullet frontal area, killing power, and recoil of representative factory loads and also of maximum and reduced power ("medium velocity") handloads for each caliber. To keep the comparison as uniform as possible we will compare factory loaded ammunition using bullet weights of 200-210 grains in each caliber and handloads using 200 grain bullets. These are the most common bullet weights in all the calibers.
The representative loads for the .338 Federal will be the Federal Vital-Shok factory offering using a 210 grain Nosler bullet (BC .400) at a MV of 2630 fps. The handloads will use the .338 Hornady 200 grain InterLock SP bullet (BC .361).
The representative loads for the .338-06 A-Square will be the Weatherby factory load using a 210 grain Nosler Partition bullet (BC .400) at a MV of 2750 fps. The reloads will use the .338 Hornady 200 grain InterLock SP bullet (BC .361).
The representative factory load for the .358 Winchester will be the Winchester Super-X offering with a 200 grain Silvertip bullet (approx. BC .294) at a MV of 2490 fps. The reloads will use the .358 Hornady 200 grain InterLock SP bullet (BC .282).
The representative factory load for the .35 Whelen will be the Remington Express load with a 200 grain PSP Core-Lokt bullet (BC .294) at a MV of 2675 fps. The representative handloads will use the .358 Hornady 200 grain Interlock SP bullet (BC .282).
The representative factory load for the .350 Rem. Mag. will be the Remington Express load with a 200 grain PSP Core-Lokt bullet (BC .294) at a MV of 2775 fps. The representative reloads will use the Hornady 200 grain Interlock SP bullet (BC .282).
By design, the selected medium velocity loads are all identical in bullet design, MV and ME. Whatever differences there are will be in other areas.
Velocity and Energy
Here are the selected factory loads for each caliber (Caliber - bullet, MV, ME):
Here are the selected maximum velocity reloads for each caliber (Caliber - bullet, MV, ME):
And here are the selected medium velocity reloads for each caliber (Caliber - bullet, MV, ME):
These lists give the muzzle velocity (MV) and muzzle energy (ME) for each load, so they are easy to compare and pretty much self explanatory. But there are some anomalies worth comment.
First of all, the .338 Federal and .358 Winchester share the same case capacity, and they shoot bullets of similar weight. At any given maximum average pressure (MAP) their MV's should be pretty much the same. But, as we see above, the .338 Federal has a substantial advantage in factory load velocity, and consequently energy. The reason is that .358 factory load ballistics were developed using 1955 vintage powders, while 338 Federal load ballistics were developed using high performance non-canister powders available in 2005.
For the reloader using canister powders and bullets of the same weight, the .338's velocity advantage will disappear and the two calibers will produce similar MV's at similar pressures, as is shown by our table of maximum velocity reloads.
All five calibers offer ME in excess of 3000 ft. lbs. with maximum power reloads and/or factory loads. Killing power is thus potentially high and adequate for all North American game if the hunter stays within the maximum point blank range (MPBR) of the cartridge, uses the right bullet, and gets that bullet into the right place. These cartridges can deliver near magnum energy without magnum recoil.
Trajectory is important because a bullet that shoots flatter is easier to place accurately as the range increases. In the interest fairness and uniformity, the following trajectory figures are for the maximum handloads, which use bullets of similar design. These figures are predicated on scoped rifles with the line of sight 1.5" above the center of the bore. Each load is zeroed at 200 yards for comparison purposes.
Due to their superior ballistic coefficient (BC), the .338 bullets fly a little flatter when launched at the same velocity as the .358 bullets. However, the difference is small, amounting to only about +1/2" at 100 yards and -1" at 300 yards (the latter being well beyond the MPBR of all of these cartridges). Such minor differences are insignificant considering the size of CXP3 game.
The sectional density (SD) of a bullet is calculated by dividing the bullet's weight (in pounds) by the square of its diameter (in inches). Note that only weight and diameter count. If you compare bullets of the same weight in different calibers, the smaller caliber will have superior SD for any given weight. That is exactly the situation we have here, where a 200 grain .338 bullet will always be superior in SD to a 200 grain .358 bullet.
Sectional density is important because, given bullets of identical design at identical velocity, the bullet with the greatest SD will penetrate the deepest. A crude example would be that at the same velocity a needle (a long and slender shape) penetrates better than a round ball (a short, fat shape) of the same weight. The deeper the wound channel (of any given diameter) in a game animal the more tissue is destroyed and the greater the killing power. Here are the SD numbers for our selected bullet weights:
The 210 grain .338 bullet, given equal construction, should be the deepest penetrator among the loads considered here. This favors the .338 Federal and the .338-06. However, factory loaded 250 grain .358" bullets with a SD of .279 are available in all three of the .35 caliber cartridges from Stars and Stripes. Stars and Stripes also offers 225 grain bullets (SD .281) in .338-06 factory loads. Medium bore bullets with a SD of about .270 or better have proven adequate for all North American game and all thin-skinned game, including the great bears and big cats, worldwide. Only the .338 Federal might have a problem with bullets of this length
Bullet Cross-Sectional Area
Bullet frontal area matters because the wider the wound cavity (of any given depth), the more tissue is destroyed and the greater the killing power. Remember that bullet cross-sectional area is independent of bullet weight. Here are the bullet cross-sectional areas for our two calibers:
The .358 bullet will, given the same percentage of bullet expansion, always punch a larger diameter hole than a .338 bullet. The advantage in cross-sectional area inevitably belongs to the .35 caliber cartridges.
Killing power is the intangible, but all important, issue that is the reason for the existence of medium bore hunting rifle cartridges. We shoot rifles that throw relatively large diameter bullets in the hope that they will kill big animals more effectively than small bore (8mm and smaller caliber) rifles. The concept of making a big hole to kill a big animal is a reasonable one, but the reality is that killing power is a very complicated subject. There are so many variables that killing power as applied to an individual big game animal cannot be accurately modeled.
Bullet cross-sectional area is one element of killing power. So are energy, bullet expansion, and penetration. The goal is to create the widest and deepest possible wound channel to destroy the greatest possible amount of some vital organ and thus bring the animal's life to a quick end.
Any number of systems have been devised over the years to predict killing power. Most of them strongly weight one particular factor--usually the author's favorite hobby horse--and have no demonstrable correlation with reality.
For the purposes of this article I'm going to use the Rifle Cartridge Killing Power Formula. This at least incorporates the common, easily quantifiable factors in a simple killing power formula. To quote from my article, "The Rifle Cartridge Killing Power Formula" (which can be found on the Tables, Charts and Lists Page):
"These factors are velocity, energy, bullet weight, sectional density (SD), and bullet cross-sectional area. Upon reflection I realized that since velocity is already the most important factor in calculating kinetic energy, it would not be necessary to incorporate it separately."
"That left the factors of energy, bullet weight, SD, and cross-sectional area. Then I received an e-mail from Ole Swang, who is a mathematician, and he pointed out that sectional density and frontal area equal bullet weight. Thus by including bullet weight separately I was, essentially, squaring its value. So I eliminated bullet weight. (But remember that, like velocity, it is actually present in the remaining factors.) That left the numbers for energy, SD, and frontal area to work with."
"Here is the formula: Energy at 100 yards (in foot pounds) x Sectional Density (taken from reloading manuals) x Bullet Frontal Area (in square inches) = Killing Power figure at 100 yards."
I chose 100 yards because it seemed to be a more realistic killing distance that at the muzzle. So here are the 100 yard killing power numbers for our various factory loads:
If we ran the numbers for the maximum reloads, the killing power numbers would generally be higher, particularly for the .358 Winchester (52.5). Choosing heavier bullets, say 225 grain for the .338-06 and 250 grain for all three of the .358 calibers, would also increase their killing power numbers. For example, the 100 yard killing power number for the .358 Win. shooting a 250 grain SP bullet at a MV of 2300 fps is 67.8. Drive a 250 grain bullet at a MV of 2400 fps from a .35 Whelen or .350 Mag. rifle and the 100 yard killing power number is 76.7.
Reduce the velocity of the 200 grain .338 bullet to 2400 fps, as in our medium velocity load, and the killing power number becomes 39.7, which is still substantial. For comparison, the 100 yard killing power number for the .270 Winchester cartridge shooting a 150 grain bullet at 2850 fps is 37.4.
Kick is the bugaboo of the medium bore calibers, and the main reason that they have never become more popular with mainstream North American hunters. Here are some approximate recoil figures for our selected factory loads, calculated for 8 pound rifles:
The cartridges that burn the most powder and launch their bullets at the highest velocity kick the hardest. Shooting standard factory loads, the .358 Win. kicks the least. No surprise there.
The recoil energy for our medium velocity loads would be considerably less across the board, as low as 19 ft. lbs. for the .338 Federal and .358 Winchester launching 200 grain bullets at 2400 fps. In the 8.5 pound rifle typical of a scoped .350 Mag., the recoil energy figure for our medium velocity load would be approximately 20 ft. lbs.
Unfortunately, the factory loads for these calibers, and all of our maximum reloads, exceed the 20 ft. lbs. of recoil energy that is (theoretically) supposed to be the upper limit for the average shooter. The medium velocity reloads stay barely within that limit, but even they considerably exceed the 15 ft. lbs. of recoil energy with which most shooters are actually comfortable.
These cartridges do, however, kick less than the .338 Winchester Magnum, which probably averages around 35 ft. lbs. of free recoil in an 8.5 pound rifle. And that is an important consideration for the hunter who needs a medium bore rifle and understands the dangers of excessive recoil.
Based purely on performance as factory loaded, the .350 Remington Magnum has an advantage over the other medium bore cartridges in most categories. It has slightly greater case capacity than .338-06 and .35 Whelen in a short action format with a very strong belted magnum case that eliminates the spectre of head spacing problems that has sometimes plagued .358 Win. and .35 Whelen rifles. And it can easily accommodate heavy 250 grain bullets when required. These factors make it a good choice for reloaders.
Realistically, all five of these cartridges are most suitable for the shooter/hunter who reloads his own ammunition. While available, factory loads are relatively scarce and expensive for all of these calibers.
For the shooter and reloader primarily interested in medium velocity handloads, and who will only seldom need maximum loads, the smaller cases of the .338 Federal and .358 Winchester are an advantage. They achieve a MV of 2400 fps using less powder and therefore generate less recoil. All five of our cartridges are fully capable of such loads using standard powders, but the small cases are more efficient.
On the other hand, the hunter/reloader purchasing a medium bore rifle to hunt the largest or dangerous game might be better served by the .338-06 A-Square, .35 Whelen, or .350 Rem. Mag. All three show a 200 fps velocity and 479 ft. lb. advantage in energy at the muzzle.
Ultimately, the choice between .338 and .358 caliber will probably come down to whether the buyer prefers sectional density or bullet frontal area. Do you (theoretically) favor a wider wound channel or a deeper wound channel?
Or the specific rifles available might govern cartridge selection. Fans of short action rifles, for example, will focus on the .338 Federal, .358 Winchester, and .350 Remington Magnum. The person who prefers something other than a bolt action rifle will likely choose the .358 Winchester in the Browning Lever-action Rifle (BLR). The hunter who yearns for a Weatherby will wind up with a .338-06, because that is the only one of our five calibers for which Weatherby chambers a rifle. The Remington bolt action fan will choose the .35 Whelen or the .350 Mag., and the Ruger M77 fan will choose the .350 Rem. Mag. or the .358 Win. Someone who wants an exceptionally light weight medium bore rifle (and can stand the increased recoil) will gravitate to the .338 Federal in the Kimber 84M rifle. And so on.
No matter how you slice it, though, these are well balanced medium bore cartridges. With the proper bullet and proper bullet placement, all can harvest any North American big game animal.
Copyright 2006, 2014 by Chuck Hawks. All rights reserved.